The invention relates to a window-type cage for an angular contact ball bearing, the cage having lubricant pockets.
The general function of cages in ball bearings is to guide balls in the rolling-contact bearing. In this arrangement, the balls run against the webs of the cage. The lubricant placed in the ball bearing also has the function of lubricating the contact between the balls and the cage to prevent direct contact between materials and thus avoid wear.
In order to keep the lubricant in the ball bearing or between the cage and the ball, lubricating pockets are formed, as shown in GB 28 35 42. However, these lubricating pockets lie in the region of the interface between the ball and the cage in the circumferential direction or the axial direction. At these locations, the cages are additionally weakened by the lubricating pockets since the cage has the smallest wall thickness here. The problem of cage wall thickness between two adjacent balls can also be solved by arranging fewer balls in the ball bearing. However, both measures have a negative effect on the life of the ball bearing.
It is the object of the invention to store lubricant between the cage and the ball of a bearing without prejudicing the strength of the cage and without having to reduce the number of balls in the rolling-contact bearing.
This object is achieved by the invention which provides particular shape and placement of lubricant pockets on the cage to avoid weakening at the ball to cage interfaces.
The essential point of the invention is to store lubricant on the cage at locations outside the bearing points between the cage and the ball in the circumferential direction and the axial direction, that is outside the locations on the cage with the smallest wall thickness. At these locations, the wall thickness of the cage is great enough that the cage is barely weakened by the additional lubricating pockets.
Shaping the lubricant pocket as a generally wedge shaped recess in the pocket surface of the window-type cage holds the lubricant in the pocket for a long time. In this arrangement, the lubricating pocket has a larger cross section in the center of the cage between the outer and the inner circumferential surface (or on the pitch circle) and the cross section becomes smaller toward the circumferential surface. The offset arrangement of the lubricant pockets below and above the center of the cage or pitch circle always arranges at least one lubricant pocket in such a way that this lubricant pocket stores the lubricant by virtue of its wedge shape (large cross section leading to small cross section), irrespective of the direction of rotation of the ball.